1. Field of the Invention
This invention relates to inhibitors of phosphatidylinositol 3-kinase (PI3K) signaling pathways used in combination with autophagy inhibitors.
2. Summary of the Related Art
The PI3Ks are a family of enzymes involved in cellular functions such as cell growth, proliferation, differentiation, motility, survival and intracellular trafficking, which in turn are involved in cancer. The PI3K pathway regulates cell growth, proliferation and survival, and is dysregulated with high frequency in human tumors. PI3K pathway activation in tumors occurs via multiple mechanisms including prevalent mutation and amplification of the PIK3CA gene (which encodes the p110 subunit of PI3Ka), or downregulation of the lipid phosphatase PTEN. Downstream of PI3K, mTOR controls cell growth and proliferation through its two distinct signaling complexes: mTORC1 and mTORC2. Given the role of PI3K signaling on critical cellular functions, an inhibitor that targets both PI3K and mTOR could provide therapeutic benefit to patient populations with tumors harboring activating mutations in PIK3CA or Ras, PTEN-deletion, or where tumors are upregulated in growth factor signaling.
Phosphatidylinositol 3-kinase (PI3Kα), a dual specificity protein kinase, is composed of an 85 kDa regulatory subunit and a 110 kDa catalytic subunit. The protein encoded by this gene represents the catalytic subunit, which uses ATP to phosphorylate PtdIns, PtdIns4P and PtdIns(4,5)P2. PTEN, a tumor suppressor which inhibits cell growth through multiple mechanisms, can dephosphorylate PIP3, the major product of PIK3CA. PIP3, in turn, is required for translocation of protein kinase B (AKT1, PKB) to the cell membrane, where it is phosphorylated and activated by upstream kinases. The effect of PTEN on cell death is mediated through the PIK3CA/AKT1 pathway.
PI3Kα has been implicated in the control of cytoskeletal reorganization, apoptosis, vesicular trafficking, proliferation and differentiation processes. Increased copy number and expression of PIK3CA is associated with a number of malignancies such as ovarian cancer (Campbell et al., Cancer Res 2004, 64, 7678-7681; Levine et al., Clin Cancer Res 2005, 11, 2875-2878; Wang et al., Hum Mutat 2005, 25, 322; Lee et al., Gynecol Oncol 2005, 97, 26-34), cervical cancer, breast cancer (Bachman, et al. Cancer Biol Ther 2004, 3, 772-775; Levine, et al., supra; Li et al., Breast Cancer Res Treat 2006, 96, 91-95; Saal et al., Cancer Res 2005, 65, 2554-2559; Samuels and Velculescu, Cell Cycle 2004, 3, 1221-1224), colorectal cancer (Samuels, et al. Science 2004, 304, 554; Velho et al. Eur J Cancer 2005, 41, 1649-1654), endometrial cancer (Oda et al. Cancer Res. 2005, 65, 10669-10673), gastric carcinomas (Byun et al., Int J Cancer 2003, 104, 318-327; Li et al., supra; Velho et al., supra; Lee et al., Oncogene 2005, 24, 1477-1480), hepatocellular carcinoma (Lee et al., id.), small and non-small cell lung cancer (Tang et al., Lung Cancer 2006, 51, 181-191; Massion et al., Am J Respir Crit. Care Med 2004, 170, 1088-1094), thyroid carcinoma (Wu et al., J Clin Endocrinol Metab 2005, 90, 4688-4693), acute myelogenous leukemia (AML) (Sujobert et al., Blood 1997, 106, 1063-1066), chronic myelogenous leukemia (CML) (Hickey and Cotter J Biol Chem 2006, 281, 2441-2450), and glioblastomas (Hartmann et al. Acta Neuropathol (Berl) 2005, 109, 639-642; Samuels et al., supra).
The mammalian target of rapamycin, mTOR, is a protein kinase that integrates both extracellular and intracellular signals of cellular growth, proliferation, and survival. Extracellular mitogenic growth factor signaling from cell surface receptors and intracellular pathways that convey hypoxic stress, energy and nutrient status all converge at mTOR. mTOR exists in two distinct complexes: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). mTORC 1 is a key mediator of transcription and cell growth (via its substrates p70S6 kinase and 4E-BP1) and promotes cell survival via the serum and glucocorticoid-activated kinase SGK, whereas mTORC2 promotes activation of the pro-survival kinase AKT. Given its central role in cellular growth, proliferation and survival, it is perhaps not surprising that mTOR signaling is frequently dysregulated in cancer and other diseases (Bjornsti and Houghton Rev Cancer 2004, 4(5), 335-48; Houghton and Huang Microbiol Immunol 2004, 279, 339-59; Inoki, Corradetti et al. Nat Genet. 2005, 37(1), 19-24).
mTOR is a member of the PIKK (PI3K-related Kinase) family of atypical kinases which includes ATM, ATR, and DNAPK, and its catalytic domain is homologous to that of PI3K. Dysregulation of PI3K signaling is a common function of tumor cells. In general, mTOR inhibition may be considered as a strategy in many of the tumor types in which PI3Ks signaling is implicated such as those discussed below.
As inhibitors of PI3Ks and mTOR the compounds disclosed herein, when combined with autophagy inhibitors, may be useful in the treatment of the following cancers: breast cancer (Nagata, Lan et al., Cancer Cell 2004, 6(2), 117-27), and loss of PTEN correlates with trastuzumab resistance (Pandolfi N Engl J Med 2004, 351(22), 2337-8; Nahta, Yu et al. Nat Clin Pract Oncol 2006, 3(5), 269-280); mantle cell lymphoma (MCL) (Dal Col, Zancai et al. Blood 2008, 111(10), 5142-51); renal cell carcinoma (Thomas, Tran et al. Nat Med 2006, 12(1), 122-7; Atkins, Hidalgo et al. J Clin Oncol 2004, 22(5), 909-18; Motzer, Hudes et al. J Clin Oncol 2007, 25(25), 3958-64); acute myelogenous leukemia (AML) (Sujobert, Bardet et al. Blood 2005, 106(3), 1063-6; Billottet, Grandage et al. Oncogene 2006, 25(50), 6648-6659; Tamburini, Elie et al. Blood 2007, 110(3), 1025-8); chronic myelogenous leukemia (CML) (Skorski, Bellacosa et al. Embo J 1997, 16(20), 6151-61; Bai, Ouyang et al. Blood 2000, 96(13), 4319-27; Hickey and Cotter Biol Chem 2006, 281(5), 2441-50); diffuse large B cell lymphoma (DLBCL) (Uddin, Hussain et al. Blood 2006, 108(13), 4178-86); several subtypes of sarcoma (Hernando, Charytonowicz et al. Nat Med 2007, 13(6), 748-53; Wan and Helman Oncologist 2007, 12(8), 1007-18); Rhabdomyosarcoma (Cao, Yu et al. Cancer Res 2008, 68(19), 8039-8048; Wan, Shen et al. Neoplasia 2006, 8(5), 394-401); ovarian cancer (Shayesteh, Lu et al. Nat Genet, 1999, 21(1), 99-102; Lee, Choi et al. Gynecol Oncol 2005, 97(1) 26-34); endometrial tumors (Obata, Morland et al. Cancer Res 1998, 58(10), 2095-7; Lu, Wu et al. Clin Cancer Res 2008, 14(9), 2543-50); non small cell lung carcinoma (NSCLC) (Tang, He et al. Lung Cancer 2006, 51(2), 181-91; Marsit, Meng et al. Hum Pathol 2005, 36(7), 768-76); small cell lung cancer, squamous lung cancer, and adenocarcinoma (Mansion, Taflan et al. Am J Respir Crit. Care Med 2004, 170(10), 1088-94); colorectal tumors (Velho, Oliveira et al. Eur J Cancer 2005, 41(11), 1649-54; Foukas, Claret et al. Nature, 2006, 441(7091), 366-370; Goel, Arnold et al. Cancer Res 2004, 64(9), 3014-21; Nassif, Lobo et al. Oncogene 2004, 23(2), 617-28; Bos Cancer Res 1989. 49(17), 4682-9; Fearon Ann N Y Acad Sci 1995, 768, 101-10); gastric carcinomas (Byun, Cho et al. Int J Cancer 2003, 104(3), 318-27); hepatocellular tumors (Lee, Soung et al. Oncogene 2005, 24(8), 1477-80; Hu, Huang et al. Cancer 2003, 97(8), 1929-40; Wan, Jiang et al. Cancer Res Clin Oncol 2003, 129(2), 100-6); melanomas (Guldberg, thor Straten et al. Cancer Res 1997, 57(17), 3660-3; Tsao, Zhang et al. Cancer Res 2000, 60(7), 1800-4; Whiteman, Thou et al. Int J Cancer 2002, 99(1), 63-7; Goel, Lazar et al. J Invest Dermatol 126(1), 2006, 154-60); pancreatic tumors (Asano, Yao et al. Oncogene 2004, 23(53), 8571-80); prostate carcinoma (Cairns, Okami et al. Cancer Res 1997, 57(22), 4997-5000; Gray, Stewart et al. Br J Cancer 1998, 78(10), 1296-300; Wang, Parsons et al. Clin Cancer Res 1998, 4(3), 811-5; Whang, Wu et al. Proc Natl Acad Sci USA 1998, 95(9), 5246-50; Majumder and Sellers Oncogene 2005, 24(50) 7465-74; Wang, Garcia et al. Proc Natl Acad Sci USA 2006, 103(5), 1480-5; Lu, Ren et al. Int J Oncol 2006, 28(1), 245-51; Mulholland, Dedhar et al. Oncogene 25(3), 2006, 329-37; Xin, Teitell et al. Proc Nail Acad Sci USA 2006, 103(20), 7789-94; Mikhailova, Wang et al. Adv Exp Med Biol 2008, 617, 397-405; Wang, Mikhailova et al. Oncogene 2008, 27(56), 7106-7117); thyroid carcinoma, particularly in the anaplastic subtype (Garcia-Rostan, Costa et al. Cancer Res 2005, 65(22), 10199-207); follicular thyroid carcinoma (Wu, Mambo et al. J Clin Endocrinol Metab 2005, 90(8), 4688-93); anaplastic large cell lymphoma (ALCL); hamaratomas (including Cowden's disease—multiple hamaratoma syndrome), angiomyelolipomas, TSC-Associated and sporadic lymphangioleiomyomatosis (Bissler, McCormack et al. N Engl J Med 2008, 358(2), 140-151); sclerosing hemangioma, a rare lung tumor (Randa M. S. Amin Pathology International 2008, 58(1), 38-44; and head and neck cancer (Gupta, McKenna et al. Clin Cancer Res 2002, 8(3), 885-892).
In particular, pancreatic cancer remains an incurable disease and current therapies result in only minimal survival benefit. Frequent activation of the PI3 kinase pathway, resulting in part from the ubiquitous presence of activations of KRAS, has been demonstrated in pancreatic ductal adenocarcinomas (PDACs) and found to be correlated with poor outcome after surgery. Constitutive activation of the PI3K pathway is an important consequence of this mutation since this pathway promotes cell survival, growth, and proliferation. Interestingly, upon testing a PI3K/mTOR inhibitor of the present invention in a panel of pancreatic cancer cell lines, Applicants found that apoptotic cell death was preceded by induction of autophagy. Autophagy inhibition resulted in enhancement of apoptosis. In agreement with these findings, the combination of a PI3K/mTOR inhibitor of the present invention with the autophagy inhibitor chloroquine in a xenograft model of pancreatic cancer resulted in significant delay of tumor growth. This suggests a possible role for the PI3Ks and mTOR inhibitors disclosed herein in combination with autophagy inhibitors, in the treatment of pancreatic adenocarcinoma.